Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 17: Poster I

HL 17.11: Poster

Monday, February 25, 2008, 16:30–19:00, Poster D

Photovoltage Induced by Microwave Radiation on AlGaAs/GaAs Hall Bars — •Tobias Krohn, Nikolai Mecking, André Wirthmann, and Detlef Heitmann — Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg

We have investigated the photovoltage that was induced by irradiating microwaves on Hall bars containing a two dimensional electron system (2DES) in a AlGaAs/GaAs heterostructure. The dimensions of the Hall bars were in the 100 µm regime. The experiments were performed at fixed frequency in a sweep of a magnetic field B that was applied perpendicularly with respect to the 2DES. The temperature was 4.2 K.

Our set up allows us to investigate a wide frequency range from 9 GHz to 170 GHz. We observe a rich mode spectrum with modes exhibiting positive or negative B dispersions, which we can model, respectively, by confined magnetoplasmon and edge magnetoplasmon modes. Both types of modes are governed by characteristic lengths. We find that these lengths reflect the dimensions in the close vicinity of the contacts, indicating that they are the origin of the induced photovoltage.

We gratefully acknowledge support through SFB 508 and BMBF 01BM461.